Conventional magnetostrictive fluid-pressure sensors include a fluid-pressure sensor which blocks a fluid flow and has an annular magnetostrictive cylinder with a lower deformable section below the fluid block surrounding the fluid and with an upper non-deformable section above the fluid block surrounding a hollow cavity. A first coil surrounds the upper section and provides a reference inductance value. A second coil surrounds the lower section and provides an inductance value corresponding to the change in permeability of the lower section caused by the pressure of the fluid against the fluid block which strains the lower section of the magnetostrictive cylinder changing its permeability. An annular air space separates the coil bobbin from the magnetostrictive cylinder, wherein the coil bobbin contains the first and second coils.
Another conventional fluid-pressure sensor is an automotive spark plug, which includes a single coil surrounding a magnetostrictive collar whose inner surface is exposed to stress waves from an internal combustion engine cylinder.
What is needed is an improved magnetostrictive fluid-pressure sensor.